Fig. 1: Imaging and structure characterization of the quasi-liquid phase at the solid–liquid interface in liquid phase TEM.

a Schematic illustration of In nanocrystals in aqueous solution. A quasi-liquid phase is observed on the surface of the In nanocrystals. The yellow, red and blue spheres represent In, O and H, respectively. The light blue, gray and yellow shading represent the liquid environment, liquid cell and electron beam, respectively. b Low- and c high-magnification TEM image of In nanocrystals in aqueous solution. d Fast Fourier Transformed (FFT) and Inverse Fast Fourier Transformed (IFFT) image from the core region enclosed in the red dashed square in c. e FFT and IFFT image from the solid–liquid interface region enclosed in the yellow square in c. The yellow ring area is the masked area for IFFT. TEM image analysis indicated that the core was crystalline, and the quasi-liquid phase was amorphous. f EELS spectra of the quasi-liquid phase (blue line) and surrounding solution (red line). In and O were both detected in the quasi-liquid phase. g Fluorescence spectra of SAF (black line) in the presence of In nanocrystals (blue line), In₂(SO₄)₃ (red line), InCl (golden line), and a mixed solution of In₂(SO₄)₃ and InCl (dashed pink line). The peak at 598 nm is attributed to the interaction between the interphase and SAF solution. h Model of In crystal with amorphous quasi-liquid phase in solution. The amorphous phase consists of In-ions, small In clusters, water and hydroxyl species.